Double Quantum Dots in Carbon Nanotubes - Condensed Matter > Mesoscale and Nanoscale PhysicsReport as inadecuate




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Abstract: We study the two-electron eigenspectrum of a carbon-nanotube double quantumdot with spin-orbit coupling. Exact calculation are combined with a simplemodel to provide an intuitive and accurate description of single-particle andinteraction effects. For symmetric dots and weak magnetic fields, thetwo-electron ground state is antisymmetric in the spin-valley degree of freedomand is not a pure spin-singlet state. When double occupation of one dot isfavored by increasing the detuning between the dots, the Coulomb interactioncauses strong correlation effects realized by higher orbital-level mixing.Changes in the double-dot configuration affect the relative strength of theelectron-electron interactions and can lead to different ground statetransitions. In particular, they can favor a ferromagnetic ground state both inspin and valley degrees of freedom. The strong suppression of the energy gapcan cause the disappearance of the Pauli blockade in transport experiments andthereby can also limit the stability of spin-qubits in quantum informationproposals. Our analysis is generalized to an array of coupled dots which isexpected to exhibit rich many-body behavior.



Author: J. von Stecher, B. Wunsch, M. Lukin, E. Demler, A. M. Rey

Source: https://arxiv.org/







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